If you haven’t heard it already (it’s gotten nearly 15 million hits on YouTube), may I present the astounding a capella Mary, Did You Know? as performed by the Pentatonix.

Check out the Pentatonix YouTube channel for more Christmas magic. Their only instruments are their voices. Even if you think you don’t know who they are, you might remember when they did a cover of Imagine Dragons’ Radioactive with violinist Lindsey Stirling.

The secret ingredient that makes their group so exceptional is bass Avi Kaplan. Who knew that such range and depth– such a luxuriant, mature tone that sounds more heavenly than earthbound– could emanate from one so young. See his and Peter Hollens’ Black is the Color of My True Love’s Hair for more of Avi.